Safety caster



Oct. 17, 1939. A c' soLEM SAFETY cAsTER f Filed Feb. 15, 1939 A Psanfedoesiv, 193e UNITED sfln'rrzs "PATENT orrjlcs ssrn'rr css'rsn.

sfumc. salem, my. man.

anpassen February 1s, 19:9. sum No. 256,214

1 (ci. 1li-44) The invention relatesx to improvements in casters for use on such articles as step ladders. work stools, portable scaffolds and various types of furniture. A6 An object of the invention is to provide a castered article of furniture which will be'freely movable except when supporting an additional weight such as vthe weight of s person or the like and-which as a result lof said additional Vweight l2 will be securely and firmly held to the floor.

Another object of the invention is to provide an improved caster which willnormally depend below the leg or supporting element so as to enable free movementof the device such as an v Il article of furniture over the floor but which will be forced within the leg upon the application of weight to the article, whereupon said article will be positioned on the iioor so as to make move'- ment of the same practically impomble until l the weight is removed.

With these and various other objects in view,

the invention may consist of certain novel fea tures of commotion and operation, as will be more fully described and particularly pointed 'ss out in the specification, drawing and claim ap pended hereto.

In the drawing which 'illustrates an 'embodiment of the invention, and wherein like reference characters are used'to designate llkepartsf 20 Figure 1 is a side elevational view showing a combination step ladder and map stool equipped with the safety casters of the invention;

K, Figure .2 is a vertical sectional view taken through a leg of the stool shown in Figure iv '2i and illustrating the interior construction ofthe caster of the invention; and f Figure 8 is a side elevational. view. parts of the caster being shown in-section.'illustrating a cantilever mounting of the same..

-' 4e Referring to the drawing, 'particularly Figure i, the combination step ladder and map'stool.

ldisclosed is of tubular construction including end frames |2 formed of tubing approximately oneinch in. diameter andv which' end frames 4l -include depending legs and a horizontal cross piece i2. The end frames are spaced andconnected by a horizontal piece of tubing I2. lAlso each end frame is provided with horizontal pieces il andiI, being suitablyl welded or otherwise 60 secured to the end frame. ihe identical pieces of the respective end'fram'are in turn'fconnected by tubular members |2 and llwhich', in addition to connecting theend Tframes', provide asupportfor thetreads il. j

Il Theuppertreadofthis combination step lad- V der and stool consists of a plurality of boards 20, I

2| and 22, having a length somewhat in excess. of the width of the frame comprising the tubular members above described. The board 20 is se'- cured to the board 2| by means of one or more 5 hinges 22 and in a somewhat similar manner board 22 is secured to the other side of board 2| Y by hinge 24. The construction of hinges 23 is such that board 2l maybe doubled back so` as to rest on board 2|. This position o'f the parts 10 is shownv in Figure 1 and in conjunction with the treads |2 a step-ladder is provided. To form a map stool the board 2d is rotated with respect to board 2| so that the former will rest on the tubular cross pieces of the end frame. Board 22 15 is swung upwardly and likewise positioned so as to rest on said'cross pieces ofthe framework.

iA relatively'large flat surface is thus provided by the three boards for supporting a map or the v like and which may be used for drawing or lay- 20 .stop limiting'the insertion within the cylinder housing of the'le'gii. Thesame may be secured to thehousing by a press fit and the parts may be Joined by means of the rivet pi n 21. The inside surface ,of thel cylinder .housing 25 is 25 machined for receiving the vcaster cylinder 28 which is adapted to have free vertical movement .with respect-tolsaid housing.' A 'set' screw 30, threaded in the cylinder housing, .projects into the slot 2|formed in and extending vertically 40 of the caster cyindein The setscrew ltherefore provides a stop. limiting movement of the caster cylinder vertically of the housing.

The inside surface of the caster cylinder at .its lower end vis smooth vsurfaced and this end, 45

by means oi a press iitreceives the ball caster 22. Above said ball caster the inside surface of the cylinder 22 is threaded for receiving the adjusting disc 22 which is formed with a recess 2l in its upper surface so that a screw driver can 50 belused to rotate the disc-to varyits position vertically ofthe caster cylinder. The coil spring v 325 is connned between said adjusting disc and a spring buii'eting disc 22 which is held by said the inwardly ledge 2t. ss

As shown in Figure 2,\th e ball caster depends below the cylinder housing and therefore said ball caster will contact the floor or other support for the combination step ladder and stool. The rubber iloor grip 38, tted to the cylinder housing in its lower end, vis accordingly positioned above and out of contact with said oor or other `support. The position of the parts above described is secured -by adjusting `the tension of each spring 35 so'that with only the weight of the article to be supported the ball casters will lbe caused to depend, or, in other words, the floor .grips will be lifted out of contact of thefloor.

The ball in each caster is held so as to freely revolve and thusthe combination step ladder and -with the iloor or other' support for the stool.

The grips are formed of rubber in order to prevent s'lippingand accordingly the combination ladder and stool by 'reason of the weight .placed thereon will be caused to securely adhere to the floor and will remainl unmovable as long as the weight continues.

The structure shown in Figure 3 illustrates a cantilever mounting of a swivel caster embodying the features ,of the present invention. In this form of the inventionthe leg 4I is'provided at its lower end with a rubber shoe 42. The bracket 43 is suitably secured tothe leg by means of the screws 44. Said bracket is provided with an opening within which is securely fitted the cylinder -housing 45. The inside surface of lsaid housing' is' machined to provide a smooth ilt for the caster cylinder 46 which is adapted to have movement vertically within the housing, said movement being limited by reason of the vertical slot 41 formed in said caster. cylinder and the set screw 48 threaded in the housing.

As explained with respect to the structure of Figure 2, the upper portionof the inside surface of the caster cylinder is threaded for receiving and adjustably positioning the disc 58. Said disc has contact with one end of the coil spring I which has contact at its other end with the buffeting disc 52. Accordingly, the spring is confined between said discs but the tension of the same may be varied by varying the position of the disc 50 vertically of the caster cylinder.`v The cylinder` 46 at its lower end receives the plug 53 forming part of theA swivel caster which additionally includes the bifurcated arms 54 and caster wheel 55. When the combination step ladder and stool o'r other article 4of furniture to which the structure of Figure 3 may be applied is supporting merely its own weight each caster wheel 55 will'be caused to depend below its rubber shoe 42. incarner words, the spring 5! within each caster cylinder has been adjusted as to tension so as to lift the article Aand thus the rubbershoesl42 are spaced from the door.

Therefore lthe article of furniture can 'be easily moved over the door, said movement being permitted by the caster wheels 55 and being Vfacilitated by the ability of the same to swivel.

However, if the weight of a person or the like is applied to the article of furniture the legs 4I will be caused to descend, whereupon the rubber shoes 42 will engage the floor. Since the shoes are of rubber they provide a non-skid support for the article, which is caused to adhere to the floor `and which remains unmovable as long as said additional weight continues.

In the structure of the invention each of the coil springs which apply tension to the caster cylinder will have to be adjusted to suit the article of furniture to which the-:same are applied. For this purpose the set screws 30 or 48 are removed and the caster cylinder withdrawn from its housing. By inserting a screw driver within the same the adjusting disc may be elevated or lowered to suit conditions.` If the adjusting disc is elevated the coil springs in assembled relation will apply greater pressure to the caster cylinder so that a heavier weight is required vbefore the non-skid rubber grips will contact the floor.

'necessary spring tension has been determined for After the a standard article of furniture the adjusting disc can be permanently xed' within its caster cylinder and the threads in the upper portion of said cylinder can be eliminated. 'The invention is not 'to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawing, as various forms o f thev device will of course be apparent to -those skilled in the artwithout departing from the spirit of the invention or the scope of the claim. s

What is claimed is: f

Acaster for articles of furniture and the like, including a cylindrical housing having securement at its upper end to a leg of said article of furniture and providing at its lower end non-skid oor gripping means, a caster cylinder mounted forlimited vertical movement within said housder, a buffeting disc positioned by said cylindrical housing above said caster cylinder, an adjusting disc within said caster cylinder, and resilient means confined between said discs for exerting a tension on said caster cylinder, the tension of said resilient means being adjusted by said adjusting disc to cause the caster thereof to depend below said v.non-slrid floor lgripping means when the article is supporting merely its own weight,

' whereby said article may be easily moved over the oor except when an additional weight is applied thereto suiilcient to compress said resilient means and cause the nonskid gripping means to contact the hoor.

' AR'I'HUR C. soLEM.

ing, a caster xed to the lower end of said .cylin- 

